In Phenomenology of Perception Merleau-Ponty tells us of how the phenomenon unfolds and its unfolding is never complete: there is no total view of being to be had. Being as phenomenon is, because of this, non-objective: it is disclosed, as Heidegger would put it, in proportion to its being concealed. Both Heidegger and Merleau-Ponty suggest, in their different ways, that this obscure counterpart to the disclosed world, forgotten in objective thought and instrumental rationality, is nonetheless shown, made visible, in art. That is to say, paraphrasing Heidegger, that art shows the concealed as concealed.

Conceptual art and its 'dematerialisation of the art object' that the art critic Lucy Lippard described during its early days, have not been readily associated with phenomenology, in part because conceptual art practices tended to be, as Lippard noted, 'non-visual'. Nonetheless, if one overlooks the apparent visual bias of Merleau-Ponty's treatment of art, then it becomes clear, as this paper set out to show, that Conceptual art's 'immaterial' or non-objective ontology is peculiarly congruent with the late Merleau-Ponty's account of the intertwining of the visible and the invisible. In particular this paper argued that the relevance to ecophenomonology of conceptual practices such as Richard Long's that consist in walking as medium and method, is not primarily in their thematising of nature or the body, but rather in their own ontological structure as open-ended and non-objective projects as opposed to their being directly perceptible objects.